Introduction

The reproductive system is designed to perpetuate the species

The male produces gametes called sperm cells

The female produces gametes called ova

The joining of a sperm cell and an ovum is fertilization

Fertilization results in the formation of a zygote

Organization of the Reproductive System

The reproductive system includes:

Gonads

Testes / Ovaries

Reproductive tract

Accessory glands

Perineal structures

External genitalia

Anatomy of the Male Reproductive System

Principal structures of the male reproductive system are:

External genitalia

Scrotum
Penis

Anatomy of the Male Reproductive System

Principal structures of the male reproductive system are (continued):

Testis

Epididymis

Ductus deferens

Ejaculatory duct

Spongy urethra (penile urethra)

Seminal gland

Prostate gland

Bulbo-urethral gland

Anatomy of the Male Reproductive System

The Testes

Testes hang inside a pouch called the scrotum, which is on the outside of the body

Testicle size

5 cm long
3 cm wide
2.5 cm thick
10–15 g

Anatomy of the Male Reproductive System

Descent of the Testes

During development, the testes form inside the abdominal cavity near the kidneys

Testes descend toward the scrotum by passing through the inguinal canals

The ductusdeferens, blood vessels, lymphatics, and nerves remain bundled to the testes in the spermaticcords

Anatomy of the Male Reproductive System

Descent of the Testes

Testicle development requires a temperature approximately 98.6°F

Hence the development of the testicles within the abdominal cavity

Sperm development requires a temperature approximately 96.6°F

Hence the development of sperm cells outside the abdominal cavity

Anatomy of the Male Reproductive System

The Spermatic Cords

Consist of:

Ilionguinal nerve
Genitofemoral nerve
Deferential artery
Ductus deferens
Pampiniform plexus

Testicular artery

Testicular vein

Anatomy of the Male Reproductive System

The Scrotum and the Position of the Testes

Divided into two chambers (scrotalcavities)

Chambers are separated by the perinealraphe

Can be seen as thickened tissue that extends from the anus, across the scrotum, and along the anterior surface of the penis

Tunica vaginalis

A serous membrane that covers the outside of each testis and covers the inside lining of each scrotal cavity

Anatomy of the Male Reproductive System

The Scrotum and the Position of the Testes (continued)

Muscles of the scrotum

Dartos muscle

Contraction causes the wrinkling of the scrotal surface

Cremaster muscle

Contraction tenses the scrotal sac and pulls it closer to the body
The temperature for sperm development is 2°F cooler than body temperature
Therefore, if the temperature is cold outside, the testes move closer to the abdomen to maintain the proper temperature

Anatomy of the Male Reproductive System

The Scrotum and the Position of the Testes (continued)

The scrotum is highly vascularized by the:

Internal pudendal arteries

A branch from the internal iliac artery

External pudendal arteries

A branch from the femoral artery

Inferior epigastric arteries

A branch from the external iliac artery

Anatomy of the Male Reproductive System

The Scrotum and the Position of the Testes (continued)

The scrotum has nerves from the:

Hypogastric plexus

Ilioinguinal nerves

Genitofemoral nerves

Pudendal nerves

Anatomy of the Male Reproductive System

Structure of the Testes

Tunica albuginea

A tough fibrous lining of the testes

Extends deep into the testes and forms septa

Septa converge toward the mediastinum

Mediastinum supports ducts that move material toward the epididymis

Tunica vaginalis

Fibrous tissue that surrounds the tunica albuginea and is continuous with the surrounding tissue of the epididymis

Anatomy of the Male Reproductive System

Histology of the Testes

The septa of the testes separate the testes into lobules

Each lobule contains seminiferous tubules

Seminiferous tubules begin to uncoil leading to the straight tubules in the mediastinum area

The straight tubules interconnect with each other forming the rete testis

Rete testis connects to the efferent ductules

Efferent ductules lead to the epididymis

Anatomy of the Male Reproductive System

Histology of the Testes (continued)

There is a space between the coils of theseminiferous tubules

The cells within this space are the interstitialcells

Interstitial cells produce and release testosterone

Anatomy of the Male Reproductive System

Histology of the Testes (continued)

Testosterone

Stimulates spermatogenesis

Promotes sperm maturation

Maintains the accessory organs

Develops secondary sex characteristics

Stimulates growth and development

Stimulates sexual behavior and sexual drive

Anatomy of the Male Reproductive System

Spermatogenesis and Meiosis

Spermatogenesis

Formation of sperm cells

Meiosis

Set of events involved in producing the sperm cells

Meiosis begins in the outer layer of the seminiferous tubules

Spermatogonia

Stem cells that will become sperm cells

Anatomy of the Male Reproductive System

Spermatogenesis and Meiosis (continued)

At sexual maturation, spermatogonia divide

One of the cells produced by this division remains in the outer layer of the seminiferous tubules as a stem cell

The other cell produced by this division differentiates to become a primaryspermatocyte

The primary spermatocyte begins to undergo meiosis

Anatomy of the Male Reproductive System

Meiosis associated with the formation of sperm cells is called spermatogenesis

The primary spermatocyte undergoes division to produce two secondary spermatocytes

Each secondary spermatocyte undergoes meiosis to produce four haploid spermatids

Each spermatid matures to become a haploidspermcell

Haploid sperm cells contain 23 chromosomes

Anatomy of the Male Reproductive System

Spermiogenesis

Spermatids will mature to form a spermatozoon (sperm cell)

This maturation process is called spermiogenesis

While the spermatids are maturing, they become embedded in nurse cells

Upon maturation, the spermatids (now sperm cells) enter into the lumen of the seminiferous tubules

Anatomy of the Male Reproductive System

Nurse Cells

Function of Nurse Cells

Maintenance of the blood–testis barrier

Support of spermatogenesis

Support of spermiogenesis

Secretion of inhibin

Controls the rate of sperm formation

Secretion of androgen-binding protein (ABP)

Binds testosterone within the seminiferous tubules so testosterone will continue to have an effect on spermiogenesis

Anatomy of the Male Reproductive System

Anatomy of a Spermatozoon

Each spermatozoon has three areas

Head

Contains chromosomes
Contains acrosomal cap consisting of enzymes
Enzyme, hyaluronidase, is necessary for fertilization of the egg

Middle piece (with the neck)

Contains mitochondria

Tail

Called the flagellum
Enables mobility of the sperm cell

Anatomy of the Male Reproductive System

The Male Reproductive Tract

Epididymis

Ductus deferens

Urethra

Anatomy of the Male Reproductive System

The Epididymis

Sperm cells move from the seminiferous tubules (via fluid movement) eventually to the epididymis to mature a little longer

The epididymis consists of three parts

Head

Receives spermatozoa via the efferent ducts

Body

Coiled tubes pass through the body

Tail

Tubes begin to uncoil to become a single tube called the ductusdeferens

Anatomy of the Male Reproductive System

Functions of the Epididymis

Monitors the composition of the fluid in the seminiferous tubules

Recycling center for damaged spermatozoa

Stores spermatozoa for further maturation (about two weeks)

Mature sperm cells are not active until they become capacitated

Anatomy of the Male Reproductive System

Functions of the Epididymis (continued)

The process of capacitation

Sperm cells become motile when mixed with secretions from the seminal glands

Become capable of fertilizing an egg when exposed to the female reproductive tract

Anatomy of the Male Reproductive System

The Ductus Deferens

Also called the vas deferens

Begins at the tail of the epididymis

Ascends into the abdominal cavity through the inguinal canal

Curves around the urinary bladder and the ureter

Descends back toward and through the prostate gland

Before entering the prostate gland, the ductus deferensexpands (ampulla) and becomes the ejaculatory duct

The ejaculatoryduct enters the prostate gland

Anatomy of the Male Reproductive System

The Urethra

Divided to form three regions

Prostatic urethra

Extends from the urinary bladder through the prostate gland

Membranous urethra

The merging of the prostatic urethra and the ejaculatory duct

Spongy urethra

Passes through the penis

Sometimes called the penile urethra

Anatomy of the Male Reproductive System

The Accessory Glands

There are three glands associated with the male reproductive system

Seminal glands (or seminal vesicles)

Prostate gland

Bulbo-urethralglands (or Cowper’sglands)

Anatomy of the Male Reproductive System

The Accessory Glands (continued)

The seminal glands

Produce 60 percent of the semen volume

Seminal fluid consists of

A high concentration of fructose

Prostaglandins

Clotting factors

Contents empty into the ductus deferens

Anatomy of the Male Reproductive System

The Accessory Glands (continued)

The prostate gland

Contents empty into the prostatic urethra

Produces 20–30 percent of the semen volume

Weakly acidic

Secretions consist of seminalplasmin

This is an antibiotic believed to prevent UTIs in males

Anatomy of the Male Reproductive System

The Accessory Glands (continued)

The bulbo-urethral glands

Paired glands located at the base of the penis

Produces 5 percent of the semen volume

Contents empty into the spongy urethra

Secretions

Consists of thick, sticky, alkaline mucus

Neutralizes urinary acids that are remaining in the urethra

Provides lubrication for the tip of the penis

Anatomy of the Male Reproductive System

Semen

Each ejaculation releases 2 to 5 ml of semen

Ejaculate material consists of:

Spermatozoa

20 million to 100 million per ml

Seminal fluid

60 percent from the seminal vesicles

30 percent from the prostate

5 percent from the bulbo-urethral glands

5 percent from the epididymis

Enzymes

Dissolves vaginal mucus and acts as an antibiotic

Anatomy of the Male Reproductive System

The Penis

Divided into three regions

Root

Attaches to the rami of the ischia

Body

Consists of erectile tissue

Glans

The expanded distal end of the penis

Surrounds the external urethral orifice

Anatomy of the Male Reproductive System

The Penis

Consists of three cylindrical columns of erectile tissue and blood vessels

Two corpora cavernosa

One corpus spongiosum

Anatomy of the Male Reproductive System

The Penis

The corpora cavernosa

Deep artery of the penis is in the center of this tissue

Each corpus cavernosum extends posteriorly forming a crus of the penis

Each crus is bound to the ramus of the ischium

The corpus spongiosum

Consists of the spongy urethra

Anatomy of the Male Reproductive System

Erection of the Penis

Parasympathetic nerves are activated

Smooth muscles in the arterial walls relax

Arterial vessels dilate

Arterial vessels and vascular channels within the corpora cavernosa become engorged with blood

Erection occurs

Anatomy of the Male Reproductive System

Semen Release and Ejaculation

The sympathetic nerves cause peristaltic action in the:

Ductus deferens

Seminal glands

Prostate gland

Bulbo-urethral glands

Ejaculation occurs

Anatomy of the Female Reproductive System

Overview of the Female Reproductive System

Ovaries

Fimbriae

Uterine tubes

Uterus

Vagina

Anatomy of the Female Reproductive System

Numerous structures aid in anchoring the ovaries, uterine tubes, and uterus

Broad ligament

Mesosalpinx

Mesovarium

Ovarian ligament

Suspensory ligament

Round ligament

Uterosacral ligament

Anatomy of the Female Reproductive System

The Ovaries

Consist of:

Cortex

Gamete production occurs here

Medulla

Anatomy of the Female Reproductive System

The Ovarian Cycle and Oogenesis

Oogenesis is the production of female gametes

Previous thoughts:

Unlike the males, this process begins before birth

Current research:

This might not be the case

Anatomy of the Female Reproductive System

The Ovarian Cycle and Oogenesis (details)

At puberty, the follicle-stimulating hormone (FSH) from the pituitary gland initiates the cycle

Primordial follicles develop into primary follicles

During this development, several layers of cells form around the follicles

Zonapellucida

This layer consists of granulosacells

These cells form interdigitating microvilli to the oocyte

These cells also produce estrogen

Anatomy of the Female Reproductive System

The Ovarian Cycle and Oogenesis (details)

The layer surrounding the zonapellucida:

Thecal cells

These cells also release estrogen

Estrogen functions

Stimulates bone and muscle growth

Maintains female secondary sex characteristics

Affects sex-related behaviors and drives

Maintains function of reproductive glands and organs

Initiates repair and growth of uterine lining

Anatomy of the Female Reproductive System

The Ovarian Cycle and Oogenesis (details)

The primary follicles develop to form secondary follicles

Secondary folliclesenlarge greatly due to fluid production by the follicular cells

Anatomy of the Female Reproductive System

The Ovarian Cycle and Oogenesis (details)

The secondary follicles become tertiary follicles

This is the mature follicle (also called Graafianfollicle)

This follicle is large enough to cause the ovarian walls to stretch

The tertiary follicle is preparing to ovulate the egg

Anatomy of the Female Reproductive System

The Ovarian Cycle and Oogenesis (details)

Ovulation: gamete release

The follicular cells around the oocyte are now called the corona radiata

There is a rise in the concentration of the luteinizinghormone (LH)—this causes a weakening in thefollicular wall

The egg is released eventually into the uterinetube

Anatomy of the Female Reproductive System

The Ovarian Cycle and Oogenesis (details)

After the release of the egg, the empty follicle is called a corpus luteum

The corpus luteum produces progesterone

Progesterone is used to prepare the body for pregnancy

If pregnancy does not occur, the corpus luteum decomposes (about 12 days after ovulation) and becomes the corpus albicans

Anatomy of the Female Reproductive System

Age and Oogenesis

At puberty, there are about 200,000 primordial follicles per ovary

Forty years later, only about 500 will have been ovulated

The rest decompose

Anatomy of the Female Reproductive System

The Uterine Tubes

Consist of four regions

Infundibulum

Ampulla

Isthmus

Uterine part

Anatomy of the Female Reproductive System

Four Regions of the Uterine Tubes

Infundibulum

Has numerous fimbriae

Inner lining of infundibulum contains cilia

Ampulla

Isthmus

Uterine part

Opens into the uterus

Anatomy of the Female Reproductive System

Histology of the Uterine Tube

Consists of

Ciliated and nonciliated columnar cells

Layers of smooth muscle

Used for peristaltic action

Successful fertilization

Occurs 12–24 hours after ovulation

Occurs in the distal 2/3 of the uterine tube (ampulla region)

Anatomy of the Female Reproductive System

The Uterus

Provides protection for the embryo

Provides nutritional support for the embryo

Provides a means to remove waste produced by the embryo

Anatomy of the Female Reproductive System

The Uterus

Overall size

Pear-shaped

7.5 cm long

5 cm diameter

30–40 g

Anatomy of the Female Reproductive System

Suspensory Ligaments of the Uterus

These are in addition to the various regions of the broad ligament

Uterosacral ligaments

Round ligaments

Cardinal ligaments

Anatomy of the Female Reproductive System

Suspensory Ligaments of the Uterus

Position of the suspensory ligaments

Uterosacral ligaments

Extend from the lateral edge of the uterus to the anterior face of the sacrum

Round ligaments

Extend from the lateral edge of the uterus just inferior to the base of the uterine tubes, pass through the inguinal canal to the connective tissue of the external genitalia

Cardinal ligaments

Extend from the base of the uterus and vagina to the lateral walls of the pelvis

Anatomy of the Female Reproductive System

Internal Anatomy of the Uterus

Consists of:

Body

Fundus

Cervix

External os

Cervical canal

Uterine cavity

Internal os

Anatomy of the Female Reproductive System

The Uterine Wall

The uterine wall consists of three layers

Endometrium

Myometrium

Consists of longitudinal, circular, and oblique smooth muscles

Perimetrium

Anatomy of the Female Reproductive System

Blood Supply to the Uterus

Uterine arteries arise from the internal iliac arteries

Ovarian arteries arise from the abdominal aorta inferior to the renal arteries

Anatomy of the Female Reproductive System

Histology of the Uterus

The endometrium is subdivided

Functional layer

This layer is closest to the uterine cavity

Contains uterine glands

Undergoes cyclic changes due to hormones

Basilar layer

This layer is closest to the myometrium

Remains relatively constant

Anatomy of the Female Reproductive System

The Uterine Cycle

The uterine cycle is the menstrual cycle

Consists of three phases

Proliferative phase

Secretory phase

Menses

Anatomy of the Female Reproductive System

Phases of the Uterine Cycle

Menarche

This is the first uterine cycle at puberty

Proliferative phase

Endometrial lining thickens preparing the body for the implantation of a fertilized egg

Secretory phase

Endometrial glands enlarge and blood vessels elongate

An egg is ready to implant (if an egg is present)

Anatomy of the Female Reproductive System

Phases of the Uterine Cycle

Menses

Begins due to a decrease in progestin and estrogen levels

This causes constriction of blood vessels

This causes a loss of the excess endometrial cells

This is menstruation

Menopause

The last uterine cycle